US4358428A - Method of removing nitrogen oxides from waste gas by selective contact reduction - Google Patents

Method of removing nitrogen oxides from waste gas by selective contact reduction Download PDF

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Publication number
US4358428A
US4358428A US06/055,977 US5597779A US4358428A US 4358428 A US4358428 A US 4358428A US 5597779 A US5597779 A US 5597779A US 4358428 A US4358428 A US 4358428A
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United States
Prior art keywords
waste gas
nitrogen oxides
sec
honeycomb
catalyst
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Expired - Lifetime
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US06/055,977
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English (en)
Inventor
Tadashi Fujita
Shigeo Soejima
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NGK Insulators Ltd
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NGK Insulators Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional [3D] monoliths

Definitions

  • This invention relates to a method of removing nitrogen oxides from waste gas exhausted from a heat power plant and any other various kinds of workshops, etc. by bringing the waste gas together with ammonia gas added thereto into contact with a catalyst and subjecting said gas to selective contact reduction.
  • honeycomb shall be understood to mean a structure having a multiplicity of parallel channels extending therethrough with each of said channels being bounded by a partition wall which is substantially uniform in thickness.
  • Waste gas exhausted from a heat power plant and any other various kinds of workshops, etc. contains a substantial amount of nitrogen oxides such as nitrogen monoxide, nitrogen dioxide, etc. Such nitrogen oxides result in public pollution such as photochemical smog, etc. and constitutes a vital social problem.
  • Such catalyst is usually impregnated into a carrier having a large specific surface area, for example, ⁇ -alumina and the carrier impregnated with the catalyst thus obtained or its kneaded shaped product is then dried and sintered.
  • Pellet-shaped, bead-shaped or honeycomb-shaped catalyst (carrier) is charged into or mounted on a reactor through which are passed waste gases together with ammonia gas at a given temperature to reduce the nitrogen oxides into nitrogen and water, thus purifying the exhausted gas.
  • an allowable pressure drop is at most 200 mm pressure head, and as a result, in order to treat a substantial amount of waste gas at a waste gas speed of higher than 10 m/sec, a waste gas duct is required to be enlarged to reduce the gas speed and make the thickness of the catalyst bed smaller than 1 m to extend the thin catalyst bed over a wide area. As a result, the apparatus practicing such prior art method becomes extremely large in size and takes up much space and hence is not economical.
  • soot and dust contained in waste gas would be so great that the bead-shaped catalyst bed, pellet-shaped catalyst bed or honeycomb-shaped catalyst having channels which are small in diameter is clogged with the soot and dust. That is, the soot and dust contained in the waste gas are adhered onto the catalyst to degrade the property of the catalyst of removing nitrogen oxides and clog the gas flow passages of the catalyst bed with the soot and dust, thus increasing the pressure drop.
  • a method of circulating a flow of catalyst particles has been proposed. But, such method is not advisable from the technical and economical standpoints.
  • the pressure drop produced in the honeycomb-shaped catalyst is substantially smaller than that produced in the bead-shaped or pellet-shaped catalyst, so that the honeycomb-shaped catalyst may be used at a relatively high waste gas speed. But, if a honeycomb-shaped catalyst each of whose channels has a small hydraulic diameter is used, the channels are clogged with soot and dust contained in the waste gas, thereby increasing the pressure drop.
  • hydraulic diameter of channels shall be understood to mean “(cross-sectional area of a channel ⁇ 4/length of inner periphery of the channel)”.
  • An object of the invention is to provide a method of removing nitrogen oxides from waste gas which can completely obviate troubles arising from the use of conventional bead-shaped, pellet-shaped and honeycomb-shaped catalysts and can efficiently remove nitrogen oxides from waste gas at a high waste gas speed without clogging the catalyst bed.
  • a feature of the invention is the provision of a method of removing nitrogen oxides from waste gas by selective contact reduction, comprising bringing the waste gas together with ammonia gas added thereto into contact with a honeycomb-shaped catalyst formed of a honeycomb-structural body under conditions that a hydraulic diameter of channels extending through the honeycomb-shaped catalyst is larger than 2.0 mm, that an open frontal area is larger than 50%, and that a waste gas speed is higher than 0.5 m/sec.
  • the invention is based on recognitions that the use of a honeycomb-shaped structural body whose pressure drop is substantially smaller than that of bead-shaped or pellet-shaped catalyst provides the important advantage that the channels are prevented from being clogged with soot and dust, etc. contained in waste gas and that nitrogen oxides can be removed at a high waste gas speed and in high yield by synergetic effect of the hydraulic diameter, open frontal area and gas speed as defined above.
  • the hydraulic diameter of each of the channels of the honeycomb-shaped catalyst is 2.0 mm to 30 mm
  • the waste gas speed is 0.5 m/sec to 60 m/sec, and that the excellent denitration effect disappears if any one of the above three conditions is not satisfied.
  • the open frontal area is smaller than 50%, the pressure drop becomes also considerably large and further the soot and dust contained in the waste gas tend to clog the channels. If the open frontal area exceeds 80%, the partition wall between two adjacent channels becomes so thin that sufficient mechanical strength of the honeycomb-shaped catalyst could not be obtained which is not desirous in practice.
  • the waste gas speed is lower than 0.5 m/sec, the soot and dust contained in the waste gas tend to clog the channels after a long time and the NO x reduction efficiency tends to be degraded if compared with that for the same SV value. If the waste gas speed exceeds 60 m/sec, the pressure drop of the honeycomb-shaped catalyst bed becomes larger than 200 mm pressure head, which is not desirous in practice.
  • honeycomb-shaped catalysts (Samples Nos. 1 to 8) each formed of cordierite ceramic body (2MgO.2Al 2 O 3 .5SiO 2 ) and having a multiplicity of parallel channels extending therethrough and hexagonal in section as shown in the drawing.
  • Samples Nos. 1 to 8 had hydraulic diameters of 2.0 mm, 7.0 mm, 14.0 mm and 30 mm and open frontal area of 50% and 80% as shown in the following Table 1.
  • the catalyst substance was comprised of 30 wt.% of V 2 O 5 , 10 wt.% of Cr 2 O 3 and 60 wt.% of ⁇ -Al 2 O 3 .
  • a reference catalyst as a Sample No. 9 having a hydraulic diameter of 1.7 mm and an open frontal area of 80% and another reference catalyst as a Sample No. 10 having a hydraulic diameter of 30 mm and an open frontal area of 40%.
  • These reference catalysts comprised the same catalyst substances as those of the Samples Nos. 1 to 8.
  • Waste gas speed 0.2 m/sec.
  • SV 3,000 hr -1 , 5,000 hr -1 , 10,000 hr -1 , 20,000 hr -1 and 30,000 hr -1 .
  • SV 3,000 hr -1 and 30,000 hr -1 after 10 hrs, 100 hrs and 1,000 hrs.
  • the NO x reduction efficiency of the Samples Nos. 1 to 8 is larger than 69% at a waste gas speed of 0.5 m/sec to 60 m/sec.
  • the higher the waste gas speed the larger the NO x reduction efficiency obtained at the same SV value.
  • the increase of the pressure drop of the Samples Nos. 1 to 8 at the waste gas speed of 0.5 m/sec to 60 m/sec is small.
  • the increase of the pressure drop of the Samples Nos. 1 to 8 at a gas speed of 0.2 m/sec becomes extremely large.
  • the pressure drop of the reference Samples Nos. 9 and 10 is suddenly increased irrespectively of the waste gas speeds. That is, in the reference Sample No. 9 whose hydraulic diameter is 1.7 mm and open frontal area is 80% and the reference Sample No. 10 whose hydraulic diameter is 30 mm and open frontal area is 40%, the soot and dust contained in the waste gas exhausted from the boiler heated exclusively by Bunker B oil cause the channels extending through the honeycomb-shaped catalyst to clog after 100 hours, thereby increasing the pressure drop.
  • the hydraulic diameter of the gas inlet side of the catalyst bed which had originally been 30 mm became smaller than 1 mm. That is, the soot and dust were rapidly deposited on that part of the honeycomb-shaped catalyst which has a large wall thickness.
  • the channel extending through the honeycomb-shaped catalyst was clogged more and more with the soot and dust which were grown starting from the above mentioned deposited product. If the open frontal area exceeds 50% and hence the wall thickness becomes thin, the above described deposition phenomenon is eliminated and the channel extending through the honeycomb-shaped catalyst is not clogged with the soot and dust. On the contrary, if the waste gas flows at a speed lower than 0.5 m/sec, the deposition phenomenon occurs thus resulting in an increase of the pressure drop.
  • the method of removing nitrogen oxides from waste gas according to the invention provides an economical way of obtaining a high denitration characteristic without increasing the pressure drop due to clogging of the channel extending through the honeycomb-shaped catalyst by removing nitrogen oxides contained in waste gas by bringing the waste gas together with ammonia gas added thereto into contact with a catalyst under conditions that the hydraulic diameter of the channel extending through the honeycomb-shaped catalyst is larger than 2.0 mm, that the open frontal area is larger than 50% and that the waste gas speed is higher than 0.5 m/sec.
  • the invention provides a method of removing nitrogen oxides from a high speed waste gas exhausted from various kinds of workshops in a high yield, which contributes greatly as a prevention against public pollution.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Catalysts (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)
US06/055,977 1975-12-24 1979-07-09 Method of removing nitrogen oxides from waste gas by selective contact reduction Expired - Lifetime US4358428A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP50154506A JPS5277878A (en) 1975-12-24 1975-12-24 Method of removing nitrogen oxides from exhaust gases
JP50-154506 1975-12-24

Related Parent Applications (1)

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US05881694 Continuation 1978-02-27

Publications (1)

Publication Number Publication Date
US4358428A true US4358428A (en) 1982-11-09

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US06/055,977 Expired - Lifetime US4358428A (en) 1975-12-24 1979-07-09 Method of removing nitrogen oxides from waste gas by selective contact reduction

Country Status (8)

Country Link
US (1) US4358428A (fr)
JP (1) JPS5277878A (fr)
BE (1) BE849821A (fr)
DE (1) DE2658539C3 (fr)
FR (1) FR2336164A1 (fr)
GB (1) GB1521010A (fr)
IT (1) IT1065501B (fr)
NL (1) NL187789C (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4645700A (en) * 1983-10-07 1987-02-24 Ngk Insulators, Ltd. Ceramic honeycomb structural body
US4732743A (en) * 1985-10-28 1988-03-22 Kali-Chemie Aktiengesellschaft Process for catalytic treatment of exhaust gases
US4755500A (en) * 1985-12-27 1988-07-05 Sakai Chemical Industry Co., Ltd. Molded catalyst for catalytic gas reactions
US4833115A (en) * 1986-09-19 1989-05-23 Dr. C. Otto Feuerfest Gmbh Ceramic honeycombed elongated catalyst carrier and method for production of same
US4874590A (en) * 1988-04-07 1989-10-17 Uop Catalytic reduction of nitrogen oxides
US4877766A (en) * 1988-07-18 1989-10-31 Corning Incorporated Mini-monolith substrate
WO1991017828A1 (fr) * 1990-05-14 1991-11-28 The University Of Akron Catalyseurs de destruction de matieres organiques halogenees
US5120516A (en) * 1990-01-08 1992-06-09 Physical Sciences, Inc. Process for removing nox emissions from combustion effluents
US5198176A (en) * 1989-03-08 1993-03-30 Fortex, Inc. Method for the manufacture of shaped products of biaxially oriented polymer material
US5206202A (en) * 1991-07-25 1993-04-27 Corning Incorporated Catalyst device fabricated in situ and method of fabricating the device
US5457268A (en) * 1990-05-14 1995-10-10 The University Of Akron Selective oxidation catalysts for halogenated organics
US5628975A (en) * 1989-02-06 1997-05-13 Nippon Shokubai Kagaku Kogyo Co., Ltd. Method for purifying exhaust gas from a diesel engine
FR2741822A1 (fr) * 1995-12-05 1997-06-06 Tami Ind Element tubulaire inorganique de filtration comportant des canaux de section non circulaire presentant des profils optimises
US20120183447A1 (en) * 2008-04-30 2012-07-19 Yul Kwan Method of reducing nitrogen oxides in a gas stream with vaporized ammonia
CN115475508A (zh) * 2022-09-28 2022-12-16 天津中材工程研究中心有限公司 Sncr旋风筒喷枪的插入位置判断方法及自动调整系统

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5824174B2 (ja) * 1977-08-31 1983-05-19 三菱重工業株式会社 排ガス処理法
JPS5477277A (en) * 1977-12-02 1979-06-20 Mitsubishi Heavy Ind Ltd Method and apparatus for reducing nitrogen oxides in combustion exhaust gas
DE3167287D1 (en) * 1980-05-27 1985-01-03 Corning Glass Works Catalytic converter
DE3128060A1 (de) * 1980-07-17 1982-04-01 Davy McKee Corp., 33803 Lakeland, Fla. Verfahren zur katalytischen kontaktoxidation von schwefeldioxid
US4373452A (en) 1980-07-28 1983-02-15 Corning Glass Works Wood burning stove
USRE33077E (en) * 1980-07-28 1989-10-03 Corning Glass Works Wood burning stove
US4520124A (en) * 1981-03-19 1985-05-28 Sakai Chemical Industry Co., Ltd. Method for producing a catalytic structure for the reduction of nitrogen oxides
JPS60183026A (ja) * 1984-03-01 1985-09-18 Mitsubishi Heavy Ind Ltd 排ガス処理法
JPS60212234A (ja) * 1984-04-05 1985-10-24 Nippon Shokubai Kagaku Kogyo Co Ltd ハニカム型脱臭触媒
JPS60220148A (ja) * 1984-04-17 1985-11-02 Nippon Shokubai Kagaku Kogyo Co Ltd ハニカム型脱臭触媒
DE3632321C1 (de) * 1986-09-19 1987-12-03 Otto Feuerfest Gmbh Verfahren und Vorrichtung zur Herstellung stranggepresster,Hohlraeume aufweisender keramischer Formkoerper
EP0482145B1 (fr) * 1990-05-08 1997-04-16 Sulzer Chemtech AG Dispositif catalyseur dans une colonne
DE4229255A1 (de) * 1992-09-02 1994-03-03 Huels Chemische Werke Ag Verfahren zur Herstellung von Katalysatoren zur Entfernung von Stickstoffoxiden aus Abgasen
DE19635385B4 (de) * 1996-08-31 2011-07-14 Envirotherm GmbH, 45136 Verfahren zur reduktiven Zerstörung von Stickstoffoxiden in staubhaltigen Abgasen aus Anlagen zur Herstellung von Zement
DE19635383A1 (de) * 1996-08-31 1998-03-05 Katalysatorenwerke Huels Gmbh DeNOx-Katalysator für stark Staub-haltige Abgase

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3502596A (en) * 1965-11-16 1970-03-24 Du Pont Ceramic structures
GB1210867A (en) * 1968-02-14 1970-11-04 Shell Int Research Process for the catalytic conversion of components in gas mixtures and an apparatus therefor
US3565830A (en) * 1963-02-07 1971-02-23 Engelhard Min & Chem Coated film of catalytically active oxide on a refractory support
US3864451A (en) * 1973-08-16 1975-02-04 Environics Inc Method for Removing Nitric Oxide from Combustion Gases
JPS5062683A (fr) * 1973-10-04 1975-05-28
US3922412A (en) * 1971-05-18 1975-11-25 Nippon Toki Kk Thin-walled carbonaceous honeycomb structures
US3958058A (en) * 1974-07-29 1976-05-18 Corning Glass Works Ultra-low expansion ceramic articles
US4026992A (en) * 1974-11-06 1977-05-31 Sumitomo Chemical Company, Limited Method for removing nitrogen oxides from combustion exhaust gases

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2247254A1 (de) * 1971-09-30 1973-04-05 British Leyland Truck & Bus Katalysatoren-traeger
JPS572375B2 (fr) * 1973-04-12 1982-01-16
JPS513147Y2 (fr) * 1973-06-20 1976-01-29
JPS523636B2 (fr) * 1973-08-17 1977-01-28
JPS5429991B2 (fr) * 1973-10-15 1979-09-27
JPS511232A (ja) * 1974-06-24 1976-01-07 Kubota Ltd Tamanegiishokukiniokeru naenookurisochi
JPS5818908B2 (ja) * 1974-09-17 1983-04-15 株式会社日立製作所 インクジエツトキロクソウチ
JPS51130693A (en) * 1975-05-10 1976-11-13 Ube Ind Ltd Catalyst for dry removal of no in exhaust gas containing dust
JPS5215476A (en) * 1975-07-28 1977-02-05 Sakai Chem Ind Co Ltd Process for treatment of exhaust gases containing nitrogen oxides and dust

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3565830A (en) * 1963-02-07 1971-02-23 Engelhard Min & Chem Coated film of catalytically active oxide on a refractory support
US3502596A (en) * 1965-11-16 1970-03-24 Du Pont Ceramic structures
GB1210867A (en) * 1968-02-14 1970-11-04 Shell Int Research Process for the catalytic conversion of components in gas mixtures and an apparatus therefor
US3922412A (en) * 1971-05-18 1975-11-25 Nippon Toki Kk Thin-walled carbonaceous honeycomb structures
US3864451A (en) * 1973-08-16 1975-02-04 Environics Inc Method for Removing Nitric Oxide from Combustion Gases
JPS5062683A (fr) * 1973-10-04 1975-05-28
US3958058A (en) * 1974-07-29 1976-05-18 Corning Glass Works Ultra-low expansion ceramic articles
US4026992A (en) * 1974-11-06 1977-05-31 Sumitomo Chemical Company, Limited Method for removing nitrogen oxides from combustion exhaust gases

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4645700A (en) * 1983-10-07 1987-02-24 Ngk Insulators, Ltd. Ceramic honeycomb structural body
US4741792A (en) * 1983-10-07 1988-05-03 Ngk Insulators, Ltd. Method of manufacturing a ceramic honeycomb structural body and an extrusion die therefor
US4732743A (en) * 1985-10-28 1988-03-22 Kali-Chemie Aktiengesellschaft Process for catalytic treatment of exhaust gases
US4755500A (en) * 1985-12-27 1988-07-05 Sakai Chemical Industry Co., Ltd. Molded catalyst for catalytic gas reactions
US4833115A (en) * 1986-09-19 1989-05-23 Dr. C. Otto Feuerfest Gmbh Ceramic honeycombed elongated catalyst carrier and method for production of same
US4874590A (en) * 1988-04-07 1989-10-17 Uop Catalytic reduction of nitrogen oxides
US4877766A (en) * 1988-07-18 1989-10-31 Corning Incorporated Mini-monolith substrate
US5628975A (en) * 1989-02-06 1997-05-13 Nippon Shokubai Kagaku Kogyo Co., Ltd. Method for purifying exhaust gas from a diesel engine
US5198176A (en) * 1989-03-08 1993-03-30 Fortex, Inc. Method for the manufacture of shaped products of biaxially oriented polymer material
US5120516A (en) * 1990-01-08 1992-06-09 Physical Sciences, Inc. Process for removing nox emissions from combustion effluents
US5457268A (en) * 1990-05-14 1995-10-10 The University Of Akron Selective oxidation catalysts for halogenated organics
WO1991017828A1 (fr) * 1990-05-14 1991-11-28 The University Of Akron Catalyseurs de destruction de matieres organiques halogenees
US5206202A (en) * 1991-07-25 1993-04-27 Corning Incorporated Catalyst device fabricated in situ and method of fabricating the device
FR2741822A1 (fr) * 1995-12-05 1997-06-06 Tami Ind Element tubulaire inorganique de filtration comportant des canaux de section non circulaire presentant des profils optimises
EP0778074A3 (fr) * 1995-12-05 1998-01-14 T.A.M.I. Industries Elément tubulaire inorganique de filtration comportant des canaux de section non circulaire présentant des profils optimisés
US5873998A (en) * 1995-12-05 1999-02-23 Societe Anonyme: T.A.M.I. Industries Inorganic tubular filter element including channels of non-circular section having optimized profile
US20120183447A1 (en) * 2008-04-30 2012-07-19 Yul Kwan Method of reducing nitrogen oxides in a gas stream with vaporized ammonia
CN115475508A (zh) * 2022-09-28 2022-12-16 天津中材工程研究中心有限公司 Sncr旋风筒喷枪的插入位置判断方法及自动调整系统
CN115475508B (zh) * 2022-09-28 2024-04-30 天津中材工程研究中心有限公司 Sncr旋风筒喷枪的插入位置判断方法及自动调整系统

Also Published As

Publication number Publication date
FR2336164A1 (fr) 1977-07-22
NL187789C (nl) 1992-01-16
JPS5277878A (en) 1977-06-30
DE2658539A1 (de) 1977-07-21
BE849821A (fr) 1977-04-15
DE2658539B2 (de) 1979-01-18
NL187789B (nl) 1991-08-16
GB1521010A (en) 1978-08-09
IT1065501B (it) 1985-02-25
NL7614370A (nl) 1977-06-28
DE2658539C3 (de) 1979-09-13
JPS5429419B2 (fr) 1979-09-22
FR2336164B1 (fr) 1981-11-27

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